U.S. patent number 5,475,496 [Application Number 08/110,767] was granted by the patent office on 1995-12-12 for image processing apparatus for binarizing multi-value image data.
This patent grant is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Shuichi Kumada.
United States Patent |
5,475,496 |
Kumada |
December 12, 1995 |
Image processing apparatus for binarizing multi-value image
data
Abstract
An image processing apparatus having a process of binarizing a
multi-value image data includes a unit for inputting a multi-value
image data and first pattern information for a binarization
process; a first memory for storing the first pattern information;
and a binarizing unit for binarizing the inputted multi-value image
data using the first pattern information stored in the first
memory. The apparatus further includes a second memory for storing
in advance second pattern information, wherein the apparatus has a
first mode during which the inputted multi-value image data is
binarized using the first pattern information, and a second mode
during which the inputted multi-value image data is binarized using
the second pattern information.
Inventors: |
Kumada; Shuichi (Yokohama,
JP) |
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JP)
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Family
ID: |
16525263 |
Appl.
No.: |
08/110,767 |
Filed: |
August 23, 1993 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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739245 |
Aug 1, 1991 |
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Foreign Application Priority Data
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Aug 3, 1990 [JP] |
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2-206551 |
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Current U.S.
Class: |
358/2.99;
358/3.06; 358/521; 358/523; 358/524 |
Current CPC
Class: |
G06K
9/38 (20130101); G06K 15/00 (20130101); H04N
1/4055 (20130101); G06K 2215/0094 (20130101); G06K
2209/01 (20130101) |
Current International
Class: |
G06K
15/00 (20060101); H04N 1/405 (20060101); H04N
001/405 (); H04N 001/56 (); H04N 001/64 () |
Field of
Search: |
;358/296,298,401,406,444,457,504,515,518,521,523,524,527,528,530 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1597773 |
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May 1970 |
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DE |
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2117208 |
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Oct 1983 |
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GB |
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Other References
Goertzel, et al., "Digital Halftoning on the IBM 4250 Printer", IBM
Journal of Research and Development, 31, (1987) Jan., No. 1, pp.
2-15, Armonk, N.Y., USA. .
Klensch, et al., "Electronically Generated Halftone Pictures", RCA
Review, Sep. 1970, pp. 517-533..
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Primary Examiner: Wong; Peter S.
Assistant Examiner: Frahm; Eric
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper &
Scinto
Parent Case Text
This application is a continuation of application Ser. No.
07/739,245, filed Aug. 1, 1991, now abandoned.
Claims
I claim:
1. An image processing apparatus for converting multi-value pixel
data representing a gradation, outputted from a host computer, into
binarized pixel data, said apparatus comprising:
means for inputting from the host computer first pattern
information for a binarization process;
first storage means for storing said first pattern information
inputted by said inputting means; and
binarizing means for binarizing inputted multi-value pixel data
using said first pattern information stored in said first storage
means, and for generating the binarized pixel data.
2. An apparatus according to claim 1, further comprising second
storage means for storing in advance second pattern information,
wherein said apparatus has a first mode during which said inputted
multi-value pixel data is binarized using said first pattern
information, and a second mode during which said inputted
multi-value pixel data is binarized using said second pattern
information.
3. An apparatus according to claim 2, wherein said second storage
means is a ROM.
4. An apparatus according to claim 2, wherein said first pattern
information and said second pattern information include patterns in
correspondence with gradations represented by said multi-value
pixel data.
5. An apparatus according to claim 4, wherein said binarizing means
reads out a pattern corresponding to a gradation represented by
said inputted multi-value pixel data from one of said first storage
means and said second storage means.
6. An apparatus according to claim 2, further comprising selecting
means for selecting one of said first mode and said second
mode.
7. An apparatus according to claim 6, wherein said selecting means
is manually selectable between one of said first mode and said
second mode.
8. An apparatus according to claim 6, wherein said selecting means
selects one of said first mode and said second mode in accordance
with a command sent from said host computer.
9. An apparatus according to claim 2, wherein in a test printing,
said apparatus prints a same multi-value pixel data on a same print
sheet using both of said first mode and said second mode.
10. An apparatus according to claim 2, wherein said first storage
means stores said first pattern information having a pattern size
different from that of said second pattern information stored in
said second storage means.
11. An apparatus according to claim 2, further comprising display
means for displaying a current mode.
12. An apparatus according to claim 2, wherein said apparatus
prints an image on a predetermined area of a print sheet in a
particular mode.
13. An apparatus according to claim 12, wherein said predetermined
area or said particular mode is designated by an operator.
14. An apparatus according to claim 12, further comprising means
for detecting, as said predetermined area, an edge portion of an
image to be printed.
15. An apparatus according to claim 1, wherein said apparatus
comprises a color image processing apparatus, and said first
storage means stores said first pattern information for each color
component.
16. An apparatus according to claim 15, wherein said apparatus
stores said first pattern information in which each color has a
different pattern size.
17. An image processing apparatus for outputting binarized pixel
data converted from multi-value pixel data supplied from an
external apparatus, said apparatus comprising:
input means for inputting from said external apparatus multi-value
pixel data representing a first gradation value and first
binarization patterns, said first binarization patterns
corresponding to a second gradation value;
a register for registering the first binarization patterns inputted
by the input means; and
a ROM, for storing in advance, a second binarization pattern
corresponding to each of the first gradation value and the second
gradation value,
wherein, after the first binarization patterns are registered in
said register, said apparatus is operable in a first mode during
which said apparatus outputs the binarized pixel data by using said
first binarization patterns and a second mode during which said
apparatus outputs the binarized pixel data by using said second
binarization pattern.
18. An apparatus according to claim 17, wherein said apparatus
comprises a color printer, and wherein said register stores said
first binarization patterns in which each color has different
binarization patterns.
19. An apparatus according to claim 18, wherein said register
stores said first binarization patterns having pattern sizes
different for each color.
20. An apparatus according to claim 6, wherein said selecting means
selects said second mode when the first pattern information is
stored in the first storage means.
21. A printing apparatus according to claim 17, further comprising
means for selecting either one of the first mode and the second
mode, wherein said selection means selects said second mode when
the first binarization patterns are stored in said register.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image processing apparatus
suitable particularly for color printing, wherein an inputted
multi-value image data is binarized to output an image such as
characters, graphics, and the like.
2. Related Background Art
In a conventional printing apparatus wherein an inputted
multi-value image data is binarized to output a color image such as
characters, graphics, and the like, a pattern necessary for a
binarization process is generated in accordance with color
designating information which designates the color of a character
or the like. Specifically, a host computer generates a multi-value
data representative of gradations of R (red), G (green), and B
(blue), or Y (yellow), M (magenta), C (cyan), and K (black), in
response to color designating commands. Upon reception of the
multi-value data from the host computer, the printing apparatus
generates binarization patterns of Y, M, C, and K having the
designated gradations, and prints out characters or the like with
designated colors.
The following disadvantages are, however, associated with the
above-described related art.
(1) A large amount of color designating information is required.
For example, if a complicated color image is to be printed, it
becomes necessary to designate a number of colors using a
corresponding number of color designating commands, and to generate
patterns as many as the number of color designating commands,
taking a long time for printing the image.
(2) Since the type of patterns to be generated are limited, it is
not possible to generate optimum binarization patterns.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the
above-described problems.
It is another object of the present invention to provide an image
processing apparatus capable of providing an optimum binarization
process matching the characteristics of a printing unit.
It is a further object of the present invention to provide an image
processing apparatus capable of providing a high speed binarization
process.
The above and other objects, and advantages of the present
invention will become more apparent from the following detailed
description and claims when read in connection with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing the structure of a printer
according to an embodiment of the present invention;
FIG. 2 shows an example of a binarization pattern registering
command;
FIGS. 3(1) to 3(4) show examples of binarization patterns;
FIGS. 4(1) to 4(3) show examples of color characters printed by
using binarization patterns;
FIG. 5 is a binarization pattern table in a binarization pattern
storage 1;
FIG. 6 shows a binarization pattern table in a binarization pattern
storage 2; and
FIGS. 7 to 10 are flow charts illustrating a procedure of printing
a color image by selectively using binarization patterns registered
by binarization pattern registering commands or previously stored
binarization patterns.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A preferred embodiment of the present invention will be described
in detail with reference to the accompanying drawings.
FIG. 1 is a block diagram showing the circuit arrangement of a
printer according to an embodiment of the present invention.
The printer 2 is connected to a host computer 1. The host computer
1 supplies print data, print commands, and the like to the printer
2 which in turn prints a necessary image.
The printer 2 has the following elements, including: an interface
21 for data transfer to and from the host computer 1, the interface
21 being constituted by a microcomputer having a ROM and RAM; a
color information storage 22 for storing information necessary for
a color reproduction process; a color reproduction unit 23 for
reproducing a color; a binarization pattern storage (RAM) 24 for
storing binarization patterns for a binarization process registered
upon input of binarization pattern registering commands (color
commands) from the host computer in accordance with color
information of characters, graphics, or the like to be printed; a
binarization pattern storage (ROM) 25 for storing binarization
patterns already generated and built in the printer; a data bus 26;
a control unit 27 for controlling the entirety of the printer; a
command analysis unit 28 for analyzing print data and binarization
pattern registering commands supplied from the host computer 1; a
dot expand unit 29 for developing a color image data processed by a
binarization pattern into dots; an output unit 30 for printing a
dot-developed data on a print sheet; and an operating panel 31 for
setting and changing parameters of printing conditions. The output
unit 30 prints out a color image by means of an electrophotographic
method, an ink jet method, or the like.
FIG. 2 shows an example of the binarization pattern registering
command (color command) sent from the host computer to the printer.
The color command is constructed of density information
(multi-value levels) and corresponding binarization pattern data
for respective colors of C, M, Y, K. In this embodiment, for an
image of 64 gradations for example, 64 color commands are used at
the initial setting to sequentially output a binarization pattern
for each multi-value level. After the initial setting, a pattern at
a desired gradation only may be changed, or a pattern for a desired
color only may be changed. The size of the pattern may be different
from that of a binarization pattern stored in ROM 25. Patterns
having different sizes between colors may be registered.
In this embodiment, the pattern size is set to 8.times.8 (pixels)
allowing a reproduction of 64 gradations. Such binarization
patterns are provided for Y, M, C, and K, respectively.
FIG. 4 shows printed characters "A" using the binarization patterns
shown in FIG. 3. In this example, the gradations of C, M, Y, and K
are designated as 100%, 50%, 25%, and 0%, respectively using the
patterns shown in FIGS. 3(1) to 3(4). The binarization patterns
shown in FIGS. 3(1) to 3(3) are developed in paint memories of C,
M, and Y. The resultant character "A" has a mixed color of C, M,
and Y. Since the binarization pattern for K is blank, no image is
developed in the paint memory of K.
FIG. 5 shows a binarization pattern table of the binarization
pattern storage (RAM) 24. The binarization pattern table shown in
FIG. 5 is prepared for each C, M, Y, and K. Each table stores
pattern addresses Pi (i=1, 2, . . . , n) each represented by a
pointer to a binarization pattern, the binarization pattern being
prepared for each multi-value level of the density information. For
example, if C has a multi-level of 64 levels (n=64) from "0" to
"63" and the value of the multi-value information of C indicates
"24", then the start address of the binarization pattern for the
multi-value information "24" is stored at the pattern address P24.
The same is also true for M, Y, and K. The addresses may be
overwritten using the binarization pattern registering command
(FIG. 2) from the host computer. "-1" in the table shown in FIG. 5
represents the end of the table.
FIG. 6 shows another binarization table in the binarization pattern
storage (ROM) 25. The binarization pattern table shown in FIG. 5 is
prepared for each C, M, Y, and K. Each table stores pattern
addresses Qi (i=1, 2, . . . , n) each represented by a pointer to a
binarization pattern, the binarization pattern being prepared for
each multi-value level of the density information.
For example, if C has a multi-level of 256 levels (n=256) from "0"
to "255" and the value of the multi-value information of C
indicates "24", then the start address of the binarization pattern
for the multi-value information "24" is stored at the pattern
address Q24. The same is also true for M, Y, and K. A pattern can
be selected in accordance with the color designating information
(multi-value information for C, M, Y, and K) from the host
computer. "-1" in the table shown in FIG. 6 represents the end of
the table.
FIGS. 7 to 10 are flow charts illustrating the procedure of reading
a binarization pattern registering command from the host computer,
registering the binarization pattern, and selecting the registered
binarization pattern (first mode) or the binarization pattern
stored in the printer, to print a color image of characters,
graphics or the like.
First, at step S1, a binarization registering command is read. At
step $2 the binarization registering pattern is analyzed at the
command analysis unit 28 to register a binarization pattern.
At step S3 a pattern selection mode is selected in response to a
mode selection command from the host computer 1.
At step S4 color designating information from the host computer is
read, the color designating information being, for example,
brightness information of designated character color R, G, B.
At step S5 a color reproduction process is executed to obtain the
density information (multi-value level) of C, M, Y, and K. The
color reproduction process includes a process of converting
brightness information of R, G, and B into density information of
C, M, Y, and K, a masking process of eliminating the influence of
unnecessary absorption characteristics of tone or ink of C, M, and
Y, a process of adjusting contrast, brightens or the like, and
other processes.
At step S6, the pattern selection mode selected at step S3 is
checked.
If the registered pattern selection mode is selected (step S7),
then at step S8 the registered binarization pattern 24 is selected.
If the stored pattern selection mode is selected (step S10), the
stored binarization pattern 25 is selected.
At step S11, in accordance with the binarization pattern selected
at step S8 or S10, the dot expand unit develops the image data into
dots, respectively for C, M, Y, and K. At step S12, a color image
is outputted. The selection between the two modes may be carried
out even on the same print sheet.
The process at step S2 will be detailed with reference to the flow
chart of FIG. 8.
First, at step S21 a pointer is shifted to the top of the
binarization pattern table for C in the binarization pattern
storage 24.
At step S22 the multi-value information (e.g., a value "24" of a
multi-value level including 64 levels from "0" to "63") for C is
taken out from the binarization pattern registering command.
At step S23 "1" is set to a constant .alpha..
At step S24 the constant .alpha. is compared with the multi-value
information for C taken out at step S22.
If the both values are not equal, at step S25 the value .alpha. and
the pointer each are incremented by 1, and thereafter the control
returns to step S24.
If the both values are equal, at step S26 the binarization pattern
for C in the binarization pattern registering command is registered
in a pattern storage area of the binarization pattern storage 24.
At step S27, the start address of the registered pattern is set to
the table. At step S28, the same processes as at steps S21 to 27
are executed for M, Y, and K.
The process at step S8 will be detailed with reference to the flow
chart shown in FIG. 9.
First, at step S81 the pointer is shifted to the top of the
binarization pattern table for C in the binarization pattern
storage 24.
At step S82 there is taken out the multi-value information (e.g., a
value "24" of the multi-value level having 64 levels from "0" to
"63") obtained at step S5.
At step S83 "1" is set to a constant .alpha..
At step S84 the constant .alpha. is compared with the multi-value
information for C taken out at step S82.
If the both values are not equal, at step S85 the value .alpha. and
the pointer each are incremented by 1, and thereafter the control
returns to step S84.
If the both values are equal, at step S86 the start address of the
binarization pattern indicated by the pointer is taken out.
At step S87, the same processes as at steps S81 to 87 are executed
for M, Y, and K.
Next, the process at step S10 will be detailed with reference to
the flow chart shown in FIG. 10.
First, at step S101 the pointer is shifted to the top of the
binarization pattern table for C in the binarization pattern
storage 25.
At step S102 there is taken out the multi-value information
obtained at step S5.
At step S103 "1" is set to a constant .alpha..
At step S104 the constant .alpha. is compared with the multi-value
information for C taken out at step S102.
If the both values are not equal, at step S105 the value .alpha.
and the pointer each are incremented by 1, and thereafter the
control returns to step S104.
If the both values are equal, at step S106 the start address of the
binarization pattern indicated by the pointer is taken out.
At step S107, the same processes as at steps S101 to 106 are
executed for M, Y, and K.
As described so far, this embodiment allows to register a
binarization pattern inputted from the host computer. One of the
registered pattern of the stored pattern built-in the printer is
selected to print out a color image of characters, graphics or the
like.
In the above-described embodiment, the pattern selection mode is
selected by the host computer. The pattern selection mode may be
selected using the operating panel of the printer.
In the above embodiment, the size of the registered binarization
pattern or the built-in binarization pattern may be set
arbitrarily.
Furthermore, one of the registered binarization pattern or the
built-in binarization pattern for each color and each multi-value
level may be selectively used.
As appreciated from the foregoing description of the present
invention, the process time required for printing can be shortened
by providing a binarization pattern previously stored. Furthermore,
by providing a binarization pattern suitable for a particular
printer, it becomes possible to realize a proper color
reproduction. Still further, a binarization pattern is inputted
from the host computer, resulting in various types of color
reproduction.
The present invention is not limited to the above embodiment, but
various modifications are possible without departing from the scope
of the present invention. For example, in a test printing, the same
multi-value data may be printed on the same print sheet using the
two modes. A current mode may be displayed on a panel or maybe
returned back to the host computer. An area for image printing may
be designated by a particular mode. A particular image area such as
an image edge portion may be separated to change a mode only for
such an image area. A plurality set of binarization pattern data
may be stored in ROM 25 or RAM 24 to select one of three modes or
more.
* * * * *